Integrated circuit comb capacitor

Abstract

The invention is directed to an integrated circuit comb capacitor with capacitor electrodes that have an increased capacitance between neighboring capacitor electrodes as compared with other interconnects and via contacts formed in the same metal wiring level and at the same pitches. The invention achieves a capacitor that minimizes capacitance tolerance and preserves symmetry in parasitic electrode-substrate capacitive coupling, without adversely affecting other interconnects and via contacts formed in the same wiring level, through the use of, at most, one additional noncritical, photomask.

1. A method for creating a capacitor, comprising the steps of:
 depositing a low-k dielectric; 
 forming a plurality of openings with same pitch in said low-k dielectric at a same metal wiring level, at least one opening a non-capacitor opening and at least one opening a capacitor opening; 
 protecting any non-capacitor opening from dielectric constant modification; 
 creating a porous region along surfaces of said at least one capacitor opening; 
 expanding said at least one capacitor opening by selectively removing said modified dielectric along said surfaces of said at least one capacitor opening; and, 
 filling said non-capacitor opening and said expanded capacitor opening with a conductive material. 
 
     
     
       2. A method as in  claim 1 , said low-k dielectric is SiCOH. 
     
     
       3. A method as in  claim 1 , said modified dielectric along said surfaces of said at least one capacitor opening removed with a diluted hydrofluoric acid. 
     
     
       4. A method as in  claim 1 , said creating step comprising depleting carbon from said surfaces of said at least one capacitor opening. 
     
     
       5. A method as in  claim 4 , said depleting comprising activating an oxidizing plasma, said activating plasma one of O 2 , N 2 O, and H 2 O. 
     
     
       6. A method as in  claim 4 , said depleting step comprising activating a reducing plasma, said reducing plasma one of N 2 /H 2  and H 2 . 
     
     
       7. A method for creating a capacitor, comprising the steps of:
 depositing a low-k dielectric comprising a dielectric matrix and porogen; 
 removing said porogen from said low-k dielectric; 
 forming a plurality of openings in said porous dielectric at same metal wiring level with same pitch, at least one opening a non-capacitor opening and at least one opening a capacitor opening; 
 protecting any non-capacitor opening from dielectric constant modification; and, 
 infusing said porous dielectric along surfaces of said capacitor opening with a material having a dielectric constant higher than said dielectric constant of said porous dielectric prior to said infusion. 
 
     
     
       8. A method as in  claim 7 , said removing step comprising:
 depleting carbon from said low-k dielectric. 
 
     
     
       9. A method as in  claim 7 , said low-k dielectric comprises SiCOH. 
     
     
       10. A method as in  claim 7 , said low-k dielectric having a dielectric constant less than 3.0, said porous dielectric with a dielectric constant between 4.0 and 5.0. 
     
     
       11. A method as in  claim 7 , said porous dielectric infused by one of one of PVD, CVD, IPVD, and ALD. 
     
     
       12. A method as in  claim 7 , said material comprises one of a metallic material and an insulating material. 
     
     
       13. A method as in  claim 8 , said depleting step comprising activating an oxidizing plasma, said activating plasma one of O 2 , N 2 O, and H 2 O. 
     
     
       14. A method as in  claim 8 , said depleting step comprising activating a reducing plasma, said reducing plasma one of N 2 /H 2  and H 2 . 
     
     
       15. A method for creating a capacitor, comprising the steps of:
 depositing a low-k dielectric comprising a porogen; 
 forming a plurality of openings with same pitch in said low-k dielectric at same metal wiring level, at least one opening a non-capacitor opening and at least one opening a capacitor opening; 
 protecting any non-capacitor opening from dielectric constant fluctuation; and, 
 infusing said porous dielectric along surfaces of said at least one capacitor opening with a material having a dielectric constant higher than said dielectric constant of said porous dielectric prior to said infusion; 
 filling said non-capacitor and capacitor openings with a conductive material; and, 
 removing porogen from said low-k dielectric. 
 
     
     
       16. A method as in  claim 15 , said removing step comprising:
 depleting carbon from said low-k dielectric. 
 
     
     
       17. A method as in  claim 15 , said low-k dielectric comprising SiCOH. 
     
     
       18. A method as in  claim 15 , said porous dielectric infused by one of one of PVD, CVD, IPVD, and ALD. 
     
     
       19. A method as in  claim 15 , said low-k dielectric having a dielectric constant less than 3.0, said porous dielectric with a dielectric constant between 4.0 and 5.0. 
     
     
       20. A method as in  claim 15 , said material comprises one of a metallic material and an insulating material. 
     
     
       21. A method as in  claim 16 , said depleting step comprising activating an oxidizing plasma, said activating plasma one of O 2 , N 2 O, and H 2 O. 
     
     
       22. A method as in  claim 16 , said depleting step comprising activating a reducing plasma, said reducing plasma one of N 2 /H 2  and H 2 .